Raloxifene, [6-hydroxy-2-(4-hydroxyphenyl)benzol[b]thien-3-yl][4-[2-(1-piperidinyl)ethoxy]phenyl-, is a well known compound having antiestrogen and antiandrogen activity. Raloxifene or raloxifene hydrochloride has proved useful for the preparation of pharmaceutical compositions for the treatment of cancer, osteoporosis and cartilage degradation.
Raloxifene, [6-hydroxy-2-(4-hydroxyphenyl)benzol[b]thien-3-yl][4-[2-(1-piperidinyl)ethoxy]phenyl-, is also known as 6-hydroxy-2-(4-hydrophenyl)-3-[4-(2-piperidinoethoxy)-benzoyl]benzo-[b]-thiophene. Other names for raloxifene may also be found in the literature.
EP 62 503 A1 discloses benzothiophene compounds and process for preparing them. The disclosed compounds have antiestrogenic and antiandrogenic activity. Pharmaceutical preparation comprising said benzothiophene compounds are described, which preparations are useful for the treatment of cancers. A particular preferred compound is Raloxifene. Acid addition salts of the benzothiophene compounds with physiologically acceptable acids are also disclosed. As examples of physiologically acceptable acids are mentioned among others sulphuric acid, succinic acid and lactic acid.
In the manufacture of raloxifene the crude product in the reaction mixture was evaporated to dryness, redissolved and purified in several steps before the pure product was recovered as a crude product that was further purified to provide the desired compound.
The obtained free base was subsequent transformed into acid addition salts using usual techniques.
EP 584 952 discloses use of raloxifene or acid addition salts thereof for the treatment of osteoporosis. It is preferred to use an acid addition salt of raloxifene instead of raloxifene as a free base because the acid addition salts generally have improved dissolution properties compared to the free base. As examples of acids used for the acid addition salts are mentioned among others: hydrochloric acid, sulphuric acid, lactic acid, malonic acid and succinic acid. Raloxifene hydrochloride is the preferred acid addition salt.
EP 652 002 A1 discloses use or 2-phenyl-3-aroylbenzothiephenes or pharmaceutical acceptable acid addition salts thereof, such as raloxifene and raloxifene hydrochloride respectively, for the inhibition of cartilage degradation.
In WO 96/09045 raloxifene hydrochloride in crystalline form or as a solvate is described.
EP 910 369 discloses raloxifene hydrochloride in crystal form where the crystals are smaller than 50 microns, and EP 826 682 discloses raloxifene in an amorphous form having enhanced solubility.
At present most commercial available pharmaceutical compositions comprising raloxifene as active ingredient comprises raloxifene hydrochloride, because raloxifene hydrochloride is fairly soluble in aqueous solvents whereas raloxifene as free base is only sparingly soluble in aqueous solvents.
Despite the extensive experimentation of increasing the bioavailability of raloxifene there is still a need for providing the active compound in a form having increased availability of the active compound in order to provide pharmaceutical preparations for oral administration, which composition have a high availability of the active compound raloxifene from the upper gastrointestinal tract.